Banca de QUALIFICAÇÃO: WALTER MUNIZ DOS SANTOS JUNIOR

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : WALTER MUNIZ DOS SANTOS JUNIOR
DATE: 21/03/2024
TIME: 09:00
LOCAL: Auditório do IF
TITLE:

Investigation of the photoluminescent properties of carbon quantum dots. Applications as a sensor and as an antimicrobial agent

KEY WORDS:

1. Nanoparticle . 2. Sensor. 3. Antimicrobial agent

PAGES: 81
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUMMARY:

Carbon dots (CDs) is a general term used to designate 0-D carbon-based nanoparticles with a core-shell structure rich in pi-conjugated domains and surface functional groups. Their remarkable optical properties render them appropriate for applications as nanosensors. In this research, we synthesized carbon dots (CD-5ANS2) co-doped with nitrogen and sulfur by using the hydrothermal synthetic method, and the azo dye precursor 5-amino-2-naphthalenesulfonic acid (CD-5ANS2) as the precursor. The thermal and pH e#ects on CD-5ANS2 photoluminescence were investigated, as well as its sensibility to metal ion and pesticide (Methomyl) doping. Our results indicate a relevant contribution of a thermally-activated mechanism to the CD-5ANS2 fluorescence. pH, ion metal, and pesticide sensibility were measured and the photoluminescence variation is probably linked with the nanoparticle surface states. The optical characteristics of CD are also explored in microbiology as potential antimicrobial agents and photosensitizers to Antimicrobial Photodynamic Therapy (aPDT). The emergence of drug-resistant pathogenic microorganisms has become a public health concern, with demand for strategies to suppress their proliferation in healthcare facilities. The present study investigates the antimicrobial properties of carbon dots (CD-MR) derived from the Methyl Red azo dye. The possibility of using CD-MR to generate reactive oxygen species (ROS) was analyzed, and a high singlet oxygen quantum e#ciency was veri#ed. Moreover, the antimicrobial activity of CD-MR was analyzed against pathogenic microorganisms Escherichia coli, Candida albicans, Staphylococcus aureus, and Cryptococcus neoformans. Kirby-Bauer susceptibility tests show that carbon dots synthesized from methyl red possess antimicrobial activity upon photoexcitation at 532 nm. The growth inhibition of C. Neoformans from CD-MR photosensitization is investigated. Our results show that N-doped carbon dots synthesized from methyl red e#ciently generate ROS and possess a strong antimicrobial activity against healthcare-relevant pathogens.

COMMITTEE MEMBERS:
Interno(a) - 1695829 - ANDRE DE LIMA MOURA
Externo(a) ao Programa - 1120709 - MARIA TEREZA DE ARAUJO - nullPresidente - 2580000 - VINICIUS MANZONI VIEIRA